#include "lvgl_port.h"

#include "cst826.h"
#include "display.h"
#include "esp_check.h"
#include "esp_log.h"
#include "esp_timer.h"
#include "freertos/FreeRTOS.h"
#include "freertos/semphr.h"
#include "freertos/task.h"

static const char *TAG = "lvgl";

#define TICK_PERIOD_MS      2
#define TASK_STACK          8192
#define TASK_PRIO           3
#define TASK_MAX_DELAY_MS   20
#define TASK_MIN_DELAY_MS   2

static SemaphoreHandle_t s_lock;
static lv_display_t *s_disp;
static lv_indev_t *s_touch_indev;

/* ---------------------------------------------------------------- tick -- */

static void tick_cb(void *arg)
{
    (void)arg;
    lv_tick_inc(TICK_PERIOD_MS);
}

/* --------------------------------------------------------------- flush -- */

static void flush_cb(lv_display_t *disp, const lv_area_t *area, uint8_t *px_map)
{
    (void)area;

    /*
     * px_map is one of the panel's own framebuffers, so this does not copy —
     * the RGB driver just switches which buffer is being scanned out and waits
     * for the switch to take effect.
     */
    esp_lcd_panel_handle_t panel = display_panel();
    esp_lcd_panel_draw_bitmap(panel, 0, 0, DISPLAY_H_RES, DISPLAY_V_RES, px_map);

    lv_display_flush_ready(disp);
}

/* --------------------------------------------------------------- input -- */

static void touch_read_cb(lv_indev_t *indev, lv_indev_data_t *data)
{
    (void)indev;

    cst826_touch_t t;
    cst826_read(&t);

    if (t.pressed) {
        data->point.x = t.x;
        data->point.y = t.y;
        data->state = LV_INDEV_STATE_PRESSED;
    } else {
        data->state = LV_INDEV_STATE_RELEASED;
    }
}

/* ---------------------------------------------------------------- task -- */

static void lvgl_task(void *arg)
{
    (void)arg;

    ESP_LOGI(TAG, "service task running");

    while (1) {
        uint32_t next = TASK_MAX_DELAY_MS;

        if (lvgl_port_lock(-1)) {
            next = lv_timer_handler();
            lvgl_port_unlock();
        }

        if (next > TASK_MAX_DELAY_MS) {
            next = TASK_MAX_DELAY_MS;
        } else if (next < TASK_MIN_DELAY_MS) {
            next = TASK_MIN_DELAY_MS;
        }

        vTaskDelay(pdMS_TO_TICKS(next));
    }
}

/* ---------------------------------------------------------------- init -- */

esp_err_t lvgl_port_init(void)
{
    if (s_disp) {
        return ESP_OK;
    }

    void *fb0 = NULL, *fb1 = NULL;
    esp_err_t err = display_get_framebuffers(&fb0, &fb1);
    if (err != ESP_OK || !fb0 || !fb1) {
        ESP_LOGE(TAG, "no framebuffers — display_init() must run first");
        return ESP_ERR_INVALID_STATE;
    }

    s_lock = xSemaphoreCreateRecursiveMutex();
    if (!s_lock) {
        return ESP_ERR_NO_MEM;
    }

    /*
     * PRD 8.2: lv_init() before creating any LVGL object. Calling
     * lv_display_create() first faults with LoadProhibited inside the TLSF
     * allocator, which is a confusing way to discover an ordering bug.
     */
    if (!lv_is_initialized()) {
        lv_init();
    }

    s_disp = lv_display_create(DISPLAY_H_RES, DISPLAY_V_RES);
    if (!s_disp) {
        return ESP_ERR_NO_MEM;
    }

    lv_display_set_color_format(s_disp, LV_COLOR_FORMAT_RGB565);
    lv_display_set_flush_cb(s_disp, flush_cb);

    size_t fb_bytes = (size_t)DISPLAY_H_RES * DISPLAY_V_RES * 2;
    lv_display_set_buffers(s_disp, fb0, fb1, fb_bytes,
                           LV_DISPLAY_RENDER_MODE_FULL);

    /* Touch, if the controller answered. The thermostat is fully usable from
     * the encoder alone, so a missing touch panel is not fatal. */
    if (cst826_is_ready()) {
        s_touch_indev = lv_indev_create();
        lv_indev_set_type(s_touch_indev, LV_INDEV_TYPE_POINTER);
        lv_indev_set_read_cb(s_touch_indev, touch_read_cb);
        lv_indev_set_display(s_touch_indev, s_disp);
    } else {
        ESP_LOGW(TAG, "touch unavailable — encoder only");
    }

    const esp_timer_create_args_t tick_args = {
        .callback = tick_cb,
        .name = "lv_tick",
    };
    esp_timer_handle_t tick_timer;
    ESP_RETURN_ON_ERROR(esp_timer_create(&tick_args, &tick_timer),
                        TAG, "tick timer");
    ESP_RETURN_ON_ERROR(
        esp_timer_start_periodic(tick_timer, TICK_PERIOD_MS * 1000),
        TAG, "tick start");

    if (xTaskCreate(lvgl_task, "lvgl", TASK_STACK, NULL, TASK_PRIO, NULL)
        != pdPASS) {
        ESP_LOGE(TAG, "task create failed");
        return ESP_ERR_NO_MEM;
    }

    ESP_LOGI(TAG, "up: %dx%d, full-refresh double buffered",
             DISPLAY_H_RES, DISPLAY_V_RES);
    return ESP_OK;
}

bool lvgl_port_lock(int timeout_ms)
{
    if (!s_lock) {
        return false;
    }
    TickType_t wait = (timeout_ms < 0) ? portMAX_DELAY
                                       : pdMS_TO_TICKS(timeout_ms);
    return xSemaphoreTakeRecursive(s_lock, wait) == pdTRUE;
}

void lvgl_port_unlock(void)
{
    if (s_lock) {
        xSemaphoreGiveRecursive(s_lock);
    }
}

lv_display_t *lvgl_port_display(void)
{
    return s_disp;
}